Sex. Did I do it for the wrong reason?

Okay, this is going to be super long, but if you have the time, please help me. So in 2014 I had been talking to this guy for awhile that was a sophomore and so was I. Well my cousin who was a senior at the time started talking to him too. And of course I had to act like I didn't care because I wasn't dating him or anything and couldn't claim him as mine. Well I had sex with him on Halloween of 2014 but about 2 or so weeks later I found out that him and my cousin had sex after we did, and I was crushed. Snd later him and her started dating. So I stopped talking to both of them for a very long time. Until about like 5 months later he messaged me and just poured his heart out to me about he missed the friendship and connection between us and couldn't bare us not being friends anymore but that he would understand if I would rather continue not talking. So I started talking to him just as friends just for a little awhile as long as he wouldn't try and anything because he was still with her. I should also add that during the entire time they were dating he always showed acts of kindness towards me and always tried to make an effort to talk to me even if I wouldn't talk back. Like for instance when I had my surgery he came by to make sure I was okay and to see if I needed anything. Me and him would always drunk text each other or call each other but we would never do anything. Anyways, him and my cousin broke up in February of 2016 and he just started to talking to me and stuff about how he was hurt and all but that he knew he did it for the right reasons. So this Sunday we both got together and hung out and got really drunk and we had sex. And I don't know if it was a good thing or a bad thing. Granted it was some of the best sex I've had and I've had a pretty good amount of sex with some several people, but nothing like that. I don't know what to do, or how to think. Please help.